Radioreceiver



March 22, 1932. E. H. SELVIG 1,850,811

RADIORECEIVER Filed March 17 1931 nxoj/g N2 gmento'z I Emar /1 Sell/g attorney i the ordinary linepower radio receiver or sound waves Patented Mar. 22, 1932'] UNITED; STATES EINAR H. SELVIG, OF ;'J.ACOMA,' WASHINGTON RADIOREGEIVER.

Application filed March 17, 193i.

This invention relates to improvements in radio receivers and provides for the reception of v.high frequency currents from either an alternating or direct current power line, thus eliminating the usual form of aerial equipment.

One object of the invention is to simplify the radio. receiver by eliminating the need of making aerial connections.

Another object is to provide a system of filtrationfor decreasing static and humming effects.

Still another object. is toprovide a volume control which governs the flow of the incoming high frequency current.

I Briefly stated the constructing a radio receiver that butzone common connection is needed for the reception of both low and high frequency current, the low frequency or power current utilized for heating the cathodes of the tubes andthe high for the operation of the head set or speaker. This single common connection is made to either an alternating or direct current power line by the usual wall pocket or lamp socket connection. Thus, in setting up a radio receiving set equipped with the apparatus set forth in this application, it is only necessary to plug into a power line, which rovides the receiver with power for its tubes, and furnishes aerial equipment therefor.

Heretofore it has been necessary'to equip with either inside or outside-aerial, in order to obtain good reception. This necessitated expense and trouble at and also expense for upkeep,since owing to weather it is often necessary to either renew the wires or to make repairs.

With the above objects in view, as will hereinafter more fully appear, the invention consists in the novel construction and arrangement of parts hereinafter described, illustrated in the accompanying drawing, and particularly pointed out in the appended claim, it being understood that various changes inform, proportions, size and minor details of structure maybe made without deinvention consists in so a located in the first radio stage o'f the {usual eing frequency-for reduction to audio the time of installation through the condensers Serial No. 523,361.

parting from the spirit or sacrificing any of the advantages of the invention.

In the accompanying drawing forming part of this specification, andin which like characters of reference indicate corresponding parts, I have diagrammatically illustrated a preferred form ofmy invention. I The characters 13 and B indicate the buss wires of apower line such as the ordinary 110 volt line as usually used for house lighting. 1 indicates aswitch in said line for turning on-or off the current. The numerals 2 and 3 indicate branch lines from the main line wires B and'B which lead respectively to the coils P5 and P of the, compound wound primary of a transformer; This transformer is type of receiver, the primaries]? and Pg'being separated by an air space or suitable insulator '15 and inductively coupled to a. secondary 8' located in the grid circuit of the first tube. Only that portion of the last named circuit, in which is-locatedthe secondary S and the Variable tuning: condenser. diagrammatic "sketch.

From the branch lines 2 and 8 respectively are' led' the'wires 4 and 5 which are connected to one side of the fixed condensers G and C the other side of the condensers C and'C are'connected by the leads (Sand 7 'toa com mon lead '8 attached to the resistance coil or similar member of a potentiometer 9.

(i ll C, is shown in the. 7

Theother ends of the primary coils P and 7 P are conductively connected to condensers l0. and 11 which are in turn connected toa common lead IQ/attached to the opposite end 3 of the potentiomete'r'9; A contactmmber,

'indicated diagrammatically by the arrow 13 moved in one direction or the other.

With the above mode of arrangement radiofrequency waves coming over the twopower supply wires B and B pass through the com-- I pound wound '1 primary (P and (P terminal of the potentiometer and (G and (C to one through movable arm or sliding contact member (13% which is grounded.

It wi 1 be obvious that by moving the sliding contact member 13 towards the terminal of the condensers (10) and (11), will cut out resistance to the flow of radio frequency currents to ground, and increase current through the coils P and P which acting inductively on secondary coil S increases the volume. t will also be obvious that by moving contact arm 13 towards the terminals of condensers C and C will cut in resistance to the flow of radio frequency currents through coils P and P by passing same direct to ground and thereby decreasing volume.

In the particular circuit shown, the two primary coils P and P are composed of 20 turns each of No. 24 B and S gauge insulated, the fixed condensers are each of .01 mfd. capacity, and the potentiometer is of 10,000 ohms resistance, but it is to be understood that the size of condensers, potentiometer, wire and number of turns of winding can be changed to conform with, and to balance with such circuit hook up used in conjunction with such coil.

The filter circuits bridging the primary coils of the radio transformer'not only serve to separate the high frequency from the low requency currents but also are utilized to filter out extraneous undesirable noises such as alternating current hum and static since the majority of these noises are caused by low frequency impulses.

Having thusset forth and disclosed the nature of this invention, what is claimed is:

In combination in a radio receiver, an alternating current power equipment, power lead-in wires to said equipment, a first stage radio transformer having a two coil primary, an insulator between said primary coils, supplementary lead wires from said power leadinto each'of said primaries, a circuit bridging each of said primaries, a potentiometer, and a set of four fixed condensers, the potentiometer located centrally and common to each of the four circuits, one of the said condensers located in each of the aforesaid cirsuits between the potentiometer and the terminals of the primarycoils, and a conductor connecting the sliding contact member of the potentiometer to ground.

In testimony whereof I afiix my signature.

. EINAR H. SELVIG. 

